1. Field of the Invention
The present invention relates to a refrigerating apparatus used to air conditioners, refrigerators and the like, and more specifically, to a refrigerating apparatus using a mixed refrigerant which does not contain chlorine.
2. Description of the Prior Art
Conventionally, so-called hydrocarbon fluoride refrigerants containing chloride such as CFC, HCFC and such like are widely used as an operating fluid for a refrigerating cycle because they are a most suitable substance as a refrigerant due to their excellent thermodynamic property and stability.
As described in, for example, Japanese Patent Publication Laid-Open No. 3-63461, Japanese Patent Publication Laid-Open No. 59-84049, Japanese Patent Publication Laid-Open No. 5-172408 and the like, it is well known that refrigerating apparatuses using these refrigerants prevent the overheat of compressors and achieve a wide range of an operating pressure.
Hydrocarbon fluoride substances containing chloride are not decomposed due to their stability and reach the stratosphere by convection. It is found that since these substances are decomposed by strong ultraviolet rays in the sky and separate chlorine atoms which react with ozone, they have an action for destroying the ozone layer. It is determined to entirely abolish the hydrocarbon fluoride substances containing chloride to protect the ozone layer which has a function to cut off ultraviolet rays harmful to human bodies in the sky. Although HCFC-22 which is widely used as a refrigerant for air conditioners and refrigerators is also an object to be abolished, since it is less effective to the destruction of the ozone layer than CFCs designated as specific freons, a longer period of grace is admitted to the substance. It is essential to develop replacement refrigerants and refrigerating apparatuses applicable to the replacement refrigerants in the period of grace.
At present, HFC-32, HFC-125, HFC-134a, HFC-143a, HFC-152a and such like, for example, as hydrocarbon fluoride refrigerants which do not contain chloride causing the destruction of the ozone layer are examined as new refrigerants to be replaced with conventional refrigerants such as HCF-C22 and such like and any one of them or a combination of a plurality of them is influential. Development is carried out aiming at a refrigerant having a performance factor such as a refrigerating capacity, efficiency and the like and a cyclic state such as an operating pressure, temperature and the like equivalent or near to those of conventional refrigerants. This is because that a caution is paid to permit the replacement refrigerants to be handled in the same manner as conventional refrigerants so that the new refrigerants can be employed with a minimum change of the specification of products and manufacturing apparatuses which have been applied to conventional refrigerants.
Incidentally, a compressor, cycle auxiliary components and a cycle control device must be arranged to comply with the new refrigerants so that a performance equivalent to that of conventional products is maintained and a cycle state such as a range of an operating pressure, temperature and the like is stabilized at all times. Further, when different refrigerants are used, refrigerator oils must be also changed to comply with the new different refrigerants. That is, although chlorine has a function for assisting compatibility with oil, new refrigerants do not contain chloride causing the destruction of the ozone layer as described above. Thus, the compatibility of the new refrigerants with conventional refrigerator oils, which are mainly composed of mineral oils, alkylbenzene and such like and have been widely used to conventional refrigerants, is greatly lowered and thus the new refrigerants cannot be used with the conventional refrigerator oils. To cope with this problem, there is developed new refrigerator oil which can secure the compatibility with the new refrigerant by the molecular polarity of ether and ester.
Incidentally, when conventional refrigerator oil and a chlorine substance contained in a conventional refrigerant are mixed in a refrigerating cycle to which a new refrigerant is applied, the new refrigerant and new refrigerator oil are chemically changed by the mixing of them, and, for example, a material used in the cooling cycle may be corroded by the occurrence of acid. Thus, a problem arises in that the reliability of products is greatly lowered.